Electrical ground net



United States Patent 3,317,650 ELECTRICAL GROUND NET Ralph M.Padellford, Nevada, Iowa, assignor to Iowa State University ResearchFoundation, Ames, Iowa, a corporation of Iowa Filed Mar. 29, 1965, Ser.No. 443,492 Claims. (Cl. 174-5) The invention described herein was madeor conceived in the course of or under a contract with the United StatesAtomic Energy Commission.

Many people must work in the close proximity of high electricalvoltages, and others are actually required in their work to handle hotlines. As a consequence, many persons are accidentally electrocuted whenthey inadvertently become grounded while they are at the same time incontact with a source of electrical energy. Devices have been created toground persons who accidentally become in contact with electricity tocarry the electrical current away from the vital organs of the body, butthese devices often unnecessarily create injury and are totallyunsatisfactory for a person who must handle hot wires.

Therefore, a principal object of this invention is to provide anelectrical ground net that will permit the wearer thereof to safelyhandle electrically energized circuits if he is not otherwise grounded,and which will come into play to direct current away from the body ifthe wearer accidentally becomes grounded.

A further object of this invention is to provide an electrical groundnet that will activate a visible or audible signal if the wearer thereofdoes become grounded so that the plight of the wearer can be quicklydiscovered by others.

A further object of this invention is to provide a ground net that willbe easily adapted for use in conjunction with garments to be worn by theelectrical worker.

A still further object of this invention is to provide a ground net thatcan be easily put on and taken off by the wearer thereof.

A still further object of this invention is to provide a ground net thatwill not interfere with the work or movements of the wearer.

A still further object of this invention is to provide a ground net thatis economical of manufacture.

These and other objects will be apparent to those skilled in the art.

This invention consists in the construction, arrangements, andcombination of the various parts of the device, whereby the objectscontemplated are attained as hereinafter more fully set forth,specifically pointed out in the claims, and illustrated in theaccompanying drawings, in which:

FIG. 1 is a schematic diagram of the electrical components of the deviceof the invention;

FIG. 2 is a perspective view of how an electrical worker might utilizethe device of this invention;

FIG. 3 is a partial perspective view of the cuff and sleeve of a garmentincorporating the device of this invention;

FIG. 4 is a perspective view of a coverall type garment utilizing thedevice of this invention with the electrical leads being shown in dottedlines;

FIG. 5 is a view of a jacket-type garment utilizing the device of thisinvention with the electrical leads being shown in dotted lines; and

FIG. 6 is a shoulder harness utilizing the device of this invention.

The numeral 10 generally designates a terminal plate of any suitableinsulative material. Terminal 12 is secured thereto by any convenientmeans, and one end of insulated electrical leads 14, 16, 18, 20 and 22are electrically secured in any suitable manner to terminal 12. Theother ends of leads 14, 16, 18, 20 and 22 are electrically connected toflexible metal bands 24, 26, 28, 30 and 32, respectively. These bandsmay be made of copper, flexible aluminum wire, or flexible woven metalmesh. Each of the bands has at least one conventional metal snap means33 secured to its opposite ends (Fig. 3) to permit the ends thereof tobe selectively secured together. The bands 24 and 26 are adapted to besecured to the ankles of the worker, the bands 28 and 30 are adapted tobe secured to the wrists of the wearer, and the band 32 is suitable forattachment around the neck of the person involved.

An insulated electrical cable 34 has one of its ends electricallysecured to terminal 12 and the other end is elec trically secured torelay switch 36 contained in housing 38. A ground cable 40 extends fromterminal 42 in housing 38 and is adapted to have its outer end connectedto a suitable electrical ground.

The relay switch 36 includes switch or shorting bar 44 that is normallyin spaced or open condition with respect to terminal 42. An electricallead 46 connects cable 34 with the coil of solenoid 48. Solenoid 48serves to close bar 44 on terminal 42 when the coils of the solenoid areelectrically excited. Lead 50 connects the solenoid coil to aconventional transducer 52 which has points that will close to passcurrent in the amount of ten milliamperes or more. The points willremain open at lesser values and this serves to prevent closing of thetransducer points by static electricity. Lead 54 connects the transducerto signal light 56 and bell means 58 which are connected in parallel toeach other and which are both connected to ground line 40. The relayswitch and the aforementioned components can be placed in either asingle housing 38 or a plurality of containers.

The bands 24, 26, 28, 30 and 32 can be included in a variety of garmentssuch as coveralls 60 or jacket 62. In each case, the outer surface ofthe bands is covered with an insulating material 64 but the innersurfaces thereof are exposed to the skin of the wearer. In FIG. 6, theterminal plate 10 is secured to a shoulder harness 66 which utilizessupporting shoulder straps 68 and waist belt 70 of conventional webbingmaterial. It is preferred that the outer surfaces of the bands also beinsulated in this embodiment of the invention.

The normal operation of the device of this invention is I as follows:The electrical worker puts on any one of the devices shown in FIGS. 4-6-and adjusts each of the bands 24, 26, 28, 30 and 32 tightly against theskin on the respective parts of his body. The ground cable 40 isconnected to any convenient ground (see ground 40A in FIG. 2), and theworker then proceeds to work in the electrical area. Since the points ofthe transducer are open, as is the shorting bar 44, the worker is notgrounded even though the cable 40 is grounded. If the worker is nototherwise grounded, such as by working in an insulated basket, he canactually handle high voltage circuits with no ill effects, becausecurrent will not pass through his body until at least some portion ofhis body becomes grounded.

In the event that the worker accidentally touches a neutral wire whilehandling hot wires, or if he inadvertently touches a hot wire whilebeing grounded (as by standing on wet ground or the like), theelectrical current will enter the body at the point of contact and tendto rush through the body to the most accessible ground. Thus, if theleft hand touches the hot wire and the right hand inadvertently touchesa ground, the current will enter the left hand, and in the absence ofthe ground net, would move through the left arm and chest of the workertowards the right arm and right hand. Even nominal voltages can be fatalunder such circumstances. However,

with the ground net herein described being worn by the electricalworker, the band 28 would immediately pick up the onrush of current andthe current would pass through insulated lead 18 to terminal 12. Thecurrent would take the path of least resistance and enter the band 28and lead 18 rather than pass through the left arm and body of theworker, for the lead 18 is a much better conductor of electricity thanis the body of the worker.

Even though the right hand is grounded, the onrush of current willcontinue to seek the path of least resistance to ground, and this pathis presented by ground cable 34 and not the lead 20- which extendstowards the right hand, for the right hand itself insulatesthe band 30from the inadvertent ground to some small degree. The initial impulse ofcurrent causes the points of transducer 52 to close and an electricalcircuit is completed through lead 46 and the coil of solenoid 48, thencethrough lead 50 and transducer -2, thence through lead 54 and throughsignal light 56 and bell means 58 to ground cable 40. This completedcircuit through the switching circuit of relay 36 energizes the coil ofsolenoid 48 and closes shorting bar 44 on terminal 42 to permit theheavy load of current to pass directly through bar 44 from cable 34 tocable 40. The light 56 and bell means 58 will be actuated by theswitching circuit of the relay 38, which will serve to notify othersthat the electrical worker is in trouble. The ground net will serve todetour the fatal charge of the electricity through the electricalconductors to ground rather than following a path through the workersbody. But most important of all, the worker will be able to actuallyhandle hot lines and the relay 36 will never be actuated (or closed)unless the worker becomes accidentally grounded, such as by touching aneutral line, and in that event, the relay will function to close thebar 44, whereupon the current will be grounded through the net ratherthan through the workers body as described above. This phenomenon willprotect the heart, respiratory and nervous systems of the worker.

The insulation on the outer surface of the bands serves to minimize theaccidental grounding of the net through the bands themselves. Obviously,all of the two types of garments in FIGS. 4 and 5 will work equally aswell, and the shoulder harness in FIG. 6 can be donned by those workerswho do not have available garments in which the ground net is anintegral part.

Thus, from the foregoing, it is seen that the device of this inventionwill accomplish at least all of its stated objectives.

Some changes may be made in the construction and arrangement of myelectrical ground net without departing from the real spirit and purposeof my invention, and it is my intention to cover by my claims, anymofiided forms of structure or use of mechanical equivalents which maybe reasonably included within their scope.

I claim:

1. In an electrical ground net device,

a first pair of electrical conducting elements adapted for connection toa wearers wrist,

a second pair of electrical conducting elements adapted for connectionto a wearers ankles,

a centrally positioned terminal means located between said pairs ofelectrical conducting elements, only a single insulated electricalconducting lead on each said electrical conducting elements, said leadsinterconnecting said terminal means with each of said respectiveelectrical conducting elements,

a single electrical ground circuit interconnecting said terminal meansand an electrical ground,

and a normally open relay switch imposed in said electrical ground sothat when said relay switch is closed,

said single electrical ground circuit will be the only means forgrounding an electrical potential imposed upon one of said electricalconducting elements.

2. The device of claim 1 wherein said electrical conducting elements arebands of electro-conducting material having an inner surface and anouter surface, the inner surface of said bands being exposed to makeelectrical contact with the body of said wearer, and insulation means onthe outer surface of said bands to prevent the inadvertent electricalcontact of said band with a source of electrical potential.

3. The device of claim 1 wherein said device is mounted on a shoulderharness whereupon said device can be secured to the upper torso of apersons body.

4. The device of claim 1 wherein said electrical conducting elements areflexible metallic members that are adapted to be wrapped tightly aroundthe limbs and neck of a persons body.

5. The device of claim 4 wherein said device includes a garment havingsleeve and cuff portions, and one of said flexible metallic members issecured to each of said cuff portions.

6. The device of claim 4 wherein said relay switch includes a controlmeans to maintain said relay switch in an open condition until apredetermined amount of electrical potential is imposed on said switch.

7. The device of claim 4 wherein said flexible metallic members includemeans to detachably hold said members in tight contact with the portionof the body upon which they are secured.

8. The device of claim 4 wherein said flexible metallic members are flatmetallic bands.

9. The device of claim 4 wherein an electrical signal device is imposedin said electrical ground circuit.

10. The device of claim 4 wherein said flexible metallic members includeinsulation means on only a portion of the outer surface thereof whichnormally would be opposite to the portion thereof adjacent the personsbody.

References Cited by the Examiner UNITED STATES PATENTS 318,172 5/1885Delaney 174-5 1,940,491 12/1933 Freitag 174-5 2,131,386 9/1938Mishelevich 340-255 2,999,189 9/1961 Gerrard 317-18 LARAMIE E. ASKIN,Primary Examiner.

J. F. RUGGERIO, Assistant Examiner.

1. IN AN ELECTRICAL GROUND NET DEVICE, A FIRST PAIR OF ELECTRICALCONDUCTING ELEMENTS ADAPTED FOR CONNECTION TO A WEARER''S WRIST, ASECOND PAIR OF ELECTRICAL CONDUCTING ELEMENTS ADAPTED FOR CONNECTION TOA WEARER''S ANKLES, A CENTRALLY POSITIONED TERMINAL MEANS LOCATEDBETWEEN SAID PAIRS OF ELECTRICAL CONDUCTING ELEMENTS, ONLY A SINGLEINSULATED ELECTRICAL CONDUCTING LEAD ON EACH SAID ELECTRICAL CONDUCTINGELEMENTS, SAID LEADS INTERCONNECTING SAID TERMINAL MEANS WITH EACH OFSAID RESPECTIVE ELECTRICAL CONDUCTING ELEMENTS, A SINGLE ELECTRICALGROUND CIRCUIT INTERCONNECTING SAID TERMINAL MEANS AND AN ELECTRICALGROUND, AND A NORMALLY OPEN RELAY SWITCH IMPOSED IN SAID ELECTRICALGROUND SO THAT WHEN SAID RELAY SWITCH IS CLOSED, SAID SINGLE ELECTRICALGROUND CIRCUIT WILL BE THE ONLY MEANS FOR GROUNDING AN ELECTRICALPOTENTIAL IMPOSED UPON ONE OF SAID ELECTRICAL CONDUCTING ELEMENTS.